May 12 2014
Tremolite is a member of the amphibole group of silicate minerals. It is formed by metamorphism of quartz and dolomite-rich sediments. It was first discovered in 1789 in Campolungo, Piumogna Valley in Ticino, Switzerland.
Properties of Tremolite
The following are the key properties of Tremolite:
- Cell Data
- Space Group: C2/m
- a = 9.863(1)
- b = 18.048(2)
- c = 5.285(1)
- β = 104.79(1)°
- Z = 2
- Crystal Data
- Monoclinic
- Point Group: 2/m
- Elongated, stout prismatic, or flattened bladed crystals, to 20cm. Also fibrous, granular or columnar aggregates
- Twinning: Simple or multiple, common || {100}; rarely multiple || {001}
- X-ray powder pattern: 8.38 (100), 3.121 (100), 2.705 (90), 3.268 (75), 1.892 (50), 2.805 (45), 2.015 (45)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| SiO2 |
56.57 |
59.3 |
| MgO |
24.41 |
24.58 |
| CaO |
12.25 |
12.03 |
| F |
1.52 |
3.84 |
| H2O+ |
1.46 |
0.5 |
| Na2O |
1.44 |
2.07 |
| Al2O3 |
1.41 |
0.26 |
| K2O |
0.68 |
0.61 |
| -O = (F, Cl)2 |
[0.64] |
[1.62] |
| FeO |
0.08 |
trace |
| Cl |
0.05 |
trace |
| MnO |
0.03 |
trace |
| TiO2 |
0.01 |
trace |
| Total |
[99.27] |
[101.57] |
- Optical Properties
- Biaxial (-)
- Orientation: Y = b
- Z ^ c = -21° to -19°
- X ^ a = -6° to -4°
- Dispersion: r < v, weak
- α = 1.605 - 1.613
- β = 1.616 - 1.624
- γ = 1.630 - 1.636
- 2V(meas.) = 86° - 88°
- Estimated Properties
| Electron density |
Bulk density (electron density)=2.98 g/cm3
note: Specific gravity of Tremolite =2.98 g/cm3 |
| Photoelectric |
PETremolite = 2.61 barns/electron
U= PETremolite x ρElectron density= 7.76 barns/cm3 |
| Fermion index |
Fermion index = 0.02
Boson index = 0.98 |
Radioactivity
|
Tremolite is not radioactive
|
How to Identify Tremolite
Pure tremolite can be found in brown, white, light-green, gray, or colorless forms. It has a transparent to translucent appearance with a white streak, vitreous luster, and fluorescent luminescence.
It can be observed as massive, fibrous, granular, or columnar structures, with perfect and distinct cleavages. The relative hardness of tremolite ranges from 5 to 6, and its average density is 3.05 g/cm3.
Global Distribution
Tremolite is distributed in the following places:
- Campolungo Alp, Ticino
- Bristenstock, Uri, Switzerland
- St. Marcel, Piedmont, Italy
- Bilin, Czech Republic
- Macomb, St. Lawrence Co. New York
- Sussex Co. New Jersey
- Lee, Berkshire Co. Massachusetts
- Wilberforce, Ontario, Canada
- Kozano, Badakhshan Province, Afghanistan
- Lelatema, Tanzania
- Brumado mine, Bahia, Brazil
Occurrence of Tremolite and Useful Mineral Association
Tremolite occurs in greenschist facies metamorphics, derived from ultramafic or magnesium carbonate rocks.
It is closely associated with winchite, riebeckite, magnesio-cummingtonite, cummingtonite, forsterite, diopside, talc, wollastonite, calcian garnet, dolomite, and calcite.
References